Repeat load within a Repeat load case

 I would like to create a REPEAT LOAD case whose constituent load cases are themselves REPEAT LOAD cases. Is this allowed? ?

You can do this if you have STAAD.Pro version 2002 or later. An example of this is shown below.

LOADING 1
SELFWEIGHT Y -1.0

LOAD 2
REPEAT LOAD
1 1.0
JOINT LOAD
4 5 FY -15. ; 11 FY -35.

LOAD 3
REPEAT LOAD
2 1.0
MEMB LOAD
8 TO 13 UNI Y -0.9 ; 6 UNI GY -1.2

LOAD 4
SELFWEIGHT Y -1.0
JOINT LOAD
4 5 FY -15. ; 11 FY -35.
MEMB LOAD
8 TO 13 UNI Y -0.9 ; 6 UNI GY -1.2

PERF ANALY
LOAD LIST 3 4
PRINT *** RES
FINISH

In the above example, load case 3 repeats load case 2, which in turn repeats load case 1.